1. The Field of the Invention
Exemplary embodiments of the invention relate to the field of vascular access devices and methods. More particularly, the invention relates to apparatus and methods for efficiently obtaining vascular access in a manner that limits blood loss by patient.
2. The Relevant Technology
An important element in any medical procedure is the control and reduction of blood lost by the subject (i.e. patient) of the procedure. Stopping blood loss is a particular concern in intravascular procedures where a laceration is made in a vein or artery so as to grant venous or arterial access. Commonly, these procedures involve the insertion, use, and removal of a guide wire, catheter, and/or other medical device to diagnose or attempt repair of a condition within the artery or vein. Intravascular procedures of this type represent a significant number of medical procedures performed each year—well into the hundreds of thousands on human patients alone—thus providing at least an equal number of procedures where blood loss is a concern for human as well as animal patients.
Accessing a vein, artery or bodily cavity typically requires entrance through a wall of the vein, artery or cavity (collectively referred to herein as “blood vessels” or “vessels”), which further requires that an access site be selected and the vessel wall be lacerated or punctured. The size of this access site is of particular concern. In general, the larger the access site, the greater the amount of blood that may escape therefrom into the surrounding body cavities and tissue. Where excessive blood is lost, the effectiveness of the medical procedure may be compromised and complications may arise.
One method to avoid or reduce the risk of excess blood loss is to reduce the size of the vascular access site. In a method commonly referred to as “micropuncture”, a multi-step process is performed to give a physician vascular access through a small access site. Generally, the physician uses a 21 gauge (0.032 inch) hypodermic needle to access the blood vessel, and a 0.018 inch guide wire is thereafter inserted into the vessel through the needle. With the guide wire in place, the needle may then be extracted from the vessel, leaving the guide wire in place.
Next, the physician places a coaxial dilator over the guide wire and inserts the dilator into the patient's vessel. The vascular wall is flexible and resilient. Accordingly, as the dilator is inserted, the initial incision is stretched to accommodate the dilator. Thus, the dilator may have an outer diameter that exceeds the initial diameter of the access site, as well as the needle used to make the access site. With the coaxial dilator in place, the guide wire and the inner dilator may be removed. The outer dilator has an internal diameter sufficient to accommodate a 0.035 inch guide wire which is then inserted. Upon insertion, the physician can then use the inserted guide wire to insert and position a catheter in a patient's vasculature. Most commonly, the catheter has a inner diameter of 0.035 inch or 0.038 inch. Once the procedure is complete, the catheter and guide wire may be removed. The access site in the vascular wall then returns to about its original size, thus reducing the patient's blood loss and recovery time.
While the micropuncture system provides vascular access in a manner that reduces blood loss and recovery time, it involves a variety of medical devices and procedures. For instance, as described above, the micropuncture system involves multiple steps and instruments. Accordingly, a need exists for devices and methods for obtaining vascular access with a reduced complexity and a reduced number of medical instruments.